Which data set is the most clustered around its mean?

To find which set is most clustered around its mean, compare how far its values are from the mean. Each set has a mean of 25 except C, whose mean is 27.5. For D, the distances from 25 are 5, 0, 10, and 5, which are smaller overall than the distances in the other sets. So D, 30, 25, 15, 30, has the least spread around its mean.

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